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Full text of "The Cambridge Natural History"

OVIDUCT

73

It is the general rule among vertebrate animals that the
ovaries are completely independent of the ducts which convey
their products to the exterior. In certain fishes, however, there
is an absolute continuity between the two structures, which is
believed to be due to a simple concrescence between the originally
distinct ovary and oviduct. The latter has grown round the
former,, an obvious advantage in preventing the eggs from
wandering into the abdominal cavity and becoming lost. In
the Mammalia we find discontinuity as a general rule. But in
quite a number of
forms folds of the
lining membrane of
the abdominal cavity
are developed, which
practically ensure
the passage of the
ova into the ovi-
duct when they are
extruded from the
ovaries. The ovi-
duct, moreover, has
a large and fiinbri-
ated mouth, called
in human anatc
—which is provided
with a number of
fanciful names —
the morsus diaboli.
This almost wraps
round the ovary, and thus prevents the ova from straying in
the wrong direction. Moreover, the ovary itself is often so
arranged . that it can. easily be withdrawn into a pocket of
the peritoneum, from which the obvious exit is by the gaping
mouth of the oviduct. This disposition of the generative parts
is still further modified in a few animals, such as the Bat1 and
the Kinkajou.2 In these animals the mouth of the oviduct
actually opens into the interior of a closed chamber which con-
tains the ovary. In this case there is but one route for the

1 KoMnson, Studies Mol. Z,ab. Owens Coll* It 1890, p. 85.
* Beddard, JProa, Zool. Soc. 1900, p. 6$7*

FIG. 47.—L&pus cunicidus. The anterior end of the vagina,
with the right uterus, Fallopian tube, and ovary. (Nat.
size.) Part of the ventral wall of the vagina is removed,
and the proximal end of the left uterus is shown in
longitudinal section. „#.£, Fallopian tube ; fl.t', its peri-
toneal aperture; l.ut, left uterus ; l.ut't left os uteri ;
ov, ovary; r.ut, right uterus ; r.-zaf', right os Titeri ; s,
vaginal septum ; -yo, vagina. (From Parker's JZootomy.)